Malicious RTF — malware analysis report

Static analysis result for SHA-256 1515d5634fc8596d…

MALICIOUS

RTF

3.6 KB First seen: 2019-03-18
MD5: 9bb915d579cb980534402a691fe8f1f6 SHA-1: d0afc96c7185a1c1ad4a4db3690dcce1f07b1ff0 SHA-256: 1515d5634fc8596db775ec3705d818f05b980628229e1d856bd1e021517b969f
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This exploit allows for arbitrary code execution upon opening the document. The presence of ` tfobjdata` and ` tfobjemb` heuristics further confirms the embedding of an OLE object, and the specific `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` firings directly point to this exploit. The ` tfobjupdate` heuristic indicates that the object is set to activate automatically.

Heuristics 5

  • Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • OLE object data medium RTF_OBJDATA
    RTF contains 1 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000003b.bin rtf-objdata-decoded RTF \objdata at offset 0x3B 1834 bytes
SHA-256: cc73cdb90af5707f804d7be97d578ea39953263e0ed6672bd2a8f24d1e05cb99

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